Nucleophilic Trifluoromethylation of Carbonyl Compounds and Disulfides with Trifluoromethane and Silicon-Containing Bases
作者:Sylvie Large、Nicolas Roques、Bernard R. Langlois
DOI:10.1021/jo000150s
日期:2000.12.1
Provided that DMF (or another N,N-dialkylformamide) is present in the reaction medium, at least in a catalytic amount, fluoroform trifluoromethylates efficiently carbonyl compounds, even enolizable ones, when opposed to (TMS)(2)N- M+, generated in situ from N(TMS)(3) and M+ F- or RO- Na+ When F- is used ina catalytic amount, silylated alpha-(trifluoromethyl)carbinols are-obtained: in this case, the four-component system HCF3/N(TMS)(3)/catalytic F-/catalytic DMF behaves like the Ruppert's reagent, especially as far as nonenolizable carbonyl compounds are concerned (CF3SiMe3 remains more efficient for enolizable carbonyl compounds). This process involves an adduct between DMF and -CF3 which is the true trifluoromethylating agent. In the same way, fluoroform efficiently trifluoromethylates disulfides and diselenides when deprotonated with a strong base selected from t-BuOK or N(SiMe3)(3)/Me4NF (or TBAT). t-BuOK is more adapted to the trifluoromethylation of aryl disulfides whereas N(SiMe3)(3)/F- is well suited to that of aliphatic disulfides.
Zinc-catalyzed regioselective C–P coupling of <i>p</i>-quinol ethers with secondary phosphine oxides to afford 2-phosphinylphenols
regioselective C–P cross coupling reaction of p-quinol ethers with secondary phosphine oxides is reported. The reaction provides a facile alternative method for the synthesis of 2-phosphinylphenols in good to high yields. Mechanistically, zinc triflate may serve as an oxophilic σ-Lewis acid to activate the C–O bond in p-quinol ether first. Then the regioselective attack of the phosphorus nucleophile at the α-carbon
Silver-Catalyzed Asymmetric Desymmetrization of Cyclohexadienones via Van Leusen Pyrrole Synthesis
作者:Mohamed Ahmed Abozeid、Hun Young Kim、Kyungsoo Oh
DOI:10.1021/acs.orglett.2c00240
日期:2022.3.11
catalytic asymmetric desymmetrization of cyclohexadienones was accomplished via Van Leusen pyrrole synthesis in the presence of a chiral silver catalyst. The ready access to chiral-fused pyrrole derivatives is attributed to the identification of a suitable isocyanomethyl sulfone surrogate, NasMIC. The current Ag(I)–chiral phosphino-carboamide ligand system can be extended to the kinetic resolution
在手性银催化剂存在下,通过 Van Leusen 吡咯合成实现了环己二烯酮的催化不对称去对称化。易于获得手性稠合吡咯衍生物归因于合适的异氰基甲基砜替代物 NasMIC 的鉴定。目前的 Ag(I)-手性膦基-碳酰胺配体系统可以扩展到外消旋环己二烯酮的动力学拆分,利用来自 AgSbF 6、手性配体 ( L *)、环己二烯酮和 NasMIC 的手性四元配合物的不同反应性。